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Full text of "An Account of a Parhelion Seen in Ireland. In Two Letters from Arthur Dobbs Esq; Of Castle Dobbs in the County of Antrim, to His Brother Mr. Richard Dobbs of Trinity-College in Dublin; and by This Last Communicated to the Royal Society"

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L An Account of a Parhelion Jeen in Ireland. In 
two Letters from Arthur Dobbs Eff^ o/Caftle 
Dobbs in the County of Antrim, to his brother 
Mr. Richard Dobbs of Trinity-'CoUege in 
Dublin 5 and by this lafl communicated to the ^yal 
Society. 

I Saw a pretty diftinguiiliable Tarhelion here on 
Thurfday Evening, of which I fend you the Ac- 
count below, as I minuted it down after I came Home, 
having been in the Fields when I law it. 

March xxd 17x^5 about half an Hour after f in the 
Afternoon nearly, I faw a diftinguilhable Tarhelton^ 
the Sun near Weji^ about an Hour high, the Wind and 
Carry of the Clouds, about N. and by E. the Sky in 
ieveral Places obfcured with light Clouds, and the Sun 
cntring into one fomewhat more watery, yet fo as to 
diltinguiili its Disk, At firft appeared belovv the Sun, 
breaking out of the Cloud, llich Rays as areufually 
fecn in an Evening, in a Sky interfperfed with Clouds, 
In a little Time appear'd at the fame H£:ight with the 
Sun, as near as I could guefs, having no Inftru- 
ment, a luminous Spot, being abou^ four Times the 
largenefs of the Sun's Disk, and about 30 D. di- 
flant from the Sun to the Sout-^ward, which was 
covered with the lively Sha^*^ of red and yellow 
on the Side next the Sun, 2^^ encreafed in Splendor 
(fo as fcarce to be born b^ ^he naked Eye) till it ex- 
ceeded the Brightnefs o^^^e Sun, which was then un- 
der a thin Cloud, {o^^ ^^^^^J ^^ perceive his Disk. 
After this had apr^^^^, ^5^.^'^^^ ^ ^^ 4 Minutes, I find- 
ing it to be a r(^^ 'rarbehon, began to look about for 
the Halo they r^^^'^^^y appear m 5 and as I obferved 

feme 



( 90 ) 

fbme Rays refembling a Glory to point upwards from 
the Sun, I faw in thole Rays at the fame Diftance (be- 
ing, as near as I could gueis, about 30 D. perpendicu* 
Jarly above the Sun) the Colours of the Hah appear- 
ing as in the luminous Spot ; but inftead of finding it, 
as I expeded, in a Circle liirrounding the liin, it was 
inverted, yet not circular, but making an obtule An- 
gle, the point towards the Sun. I then looked to 
the Northward of the Sun, and as the Cloud, which 
was thicker on that fide, moved Southwardly, alumi- 
Bous Spot began to appear at the lame Diilance from 
the Sun as the other, and in the fame Parallel of Alti- 
tude, which had the lame Colours towards the Sun, 
and increaled in Brightnefs, but did not come up to the 
Brightneft of the other Spot, yet was as luminous as 
the Sun then appeared : this Spot was very little big- 
ger than the Sun's Disk. As the Cloud mov'd on, till 
It came to about 60 D. to the Southward of the Sun, 
and 30 D. from the Spot, at an equal Height there ap- 
peared another Spot tinged with the Colours of the 
Rainbow. The whole Appearance lafled a Quarter 
of an Hour. The Reafon of my not feeing the Halo's. 
which generally appear with them, was, that there 
was a good deal of clear Sky above the Sun, and the 
Cloud was tco thick below^ it. 



Cafk "Dobbs, 
Mm^chthe z^th ly 

Arthur T)obbs\ 



'% 



( 9^ ) 

I Have fent you, as you defired, the Scheme of the 
^arhelion^ with all the Notes that I cou'd take in 
the Ihort Time it continued, having been only out oc- 
cafionally, without any Inftrument to compute the 
Proportions, or take Angles ; {o that my Oblervation 
cannot be exacSt, but only approach the Truth. 
However I can recolledt nothing material, that I have 
omitted. 

A. The Place of the Sun, being nearly Weft about 
IX or 13 D. above the Horizon, being about an Hour 
before Sun-let. 

B. The luminous Spot, being about 30 D. to the South- 
ward of the Sun, as near as I cou'd compute, hav- 
ing no Inftrument to take the Angle, and in the fame 
Parallel of Altitude ; the Spot was not fo well defin'd 
as in the Scheme, being more imperceptibly iliaded 
off in the Cloud, the two lemicircular Lines next the 
Sun were thofe tinged with the Colours ; the near- 
eft the Sun being of a deep Scarlet, the inner one a 
deep yellow, both the Colours being Ibftned as 
they fell off from the Sun, all the reft of the Spot 
being an intenfe Light, {o as the naked Eye cou'd 
Icarce bear it. 

C. The other Spot to the Northward, which appear- 
ed fometime after that marked B, being not quite ^o 
large, nor the Colours {o intenfe, but the fame way 
dilpofed, thofe next the Sun being red, the next yel- 
low, and the reft white, 

D. A Spot in the Cloud, as it moved Southwardly, till 
it came to about 60 D. Diftance from the Sun which 
had the Colours as in the other Spots, that next 
the Sun being red, the next yellow, but much fainter 
than in the Tarhelia. 



The 



( pi ) 

E. The Appearance of two Segments of Circles, at 
about the lame Diftance from the Sun, as the Tar^ 
heliaj being perpendicularly above % the Colours 
being fainter than in the Tarhelia, but the fame Way 
diipos'4 the lower Lines next the Sun acpreffing 
the red, and the upper the yellow. 

The Colours at D, and E, as they were not fb in- 
tenfe, neither were they quite fo broad as thofe at B 
and C ; the two Colours being added together were 
about 1 of the Disk at B, and the Colours in the fame 
Proportion at C ; the Diameter of the Tarhelkn at 
B, being about double the apparent Diameter of the 
Sun, as near as J could compute, as in the Scheme is 
exprels'd. 

The Centres of the Segments of the Halo's mark'd 
E, if not in the Tarhelia^ were very little below 'em. 

Below the Sun and Tarhelia the Cloud was too 
thick to difcover any thing thro' it ; and above them, 
till near the Segments jnark'd E, the Sky was ferene 
and nothing obfcured ; but at E, where the Rays, 
which pointed upwards from the Sun, terminated, it 
appear'd hazy, and fb thick as to refled:the Colours, 



CafileT>obbsj 



Arthur "D^bbs. 



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